Heat dissipating device and method of manufacture thereof

ABSTRACT

A heat dissipating device and a method of fabricating thereof, the device comprising a first base adapted to be placed in contact with a heat emitter and first heat-dissipating fins extending from the first base on at least part of a periphery of the first base. The method comprises providing a first sheet of heat conductive and mechanically resistant material; cutting, out of the first sheet of material, a first piece comprising a first central part and first tabs extending radially from the first central part; and erecting the first tabs up from the first central part.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims benefit, under 35 U.S.C. §119(e), of U.S. provisional application serial No. 61/414,157, filed on Nov. 16, 2010. All documents above are incorporated herein in their entirety by reference.

FIELD OF THE INVENTION

The present invention relates to heat dissipating devices.

SUMMARY OF THE INVENTION

More specifically, in accordance with the present invention, there is provided a heat dissipating device comprising a first base adapted to be placed in contact with a heat emitter and first heat-dissipating fins extending from the first base on at least part of a periphery of the first base.

There is further provided a method of fabricating a heat dissipating device, comprising providing a first sheet of heat conductive and mechanically resistant material; cutting, out of the first sheet of material, a first piece comprising a first central part and first tabs extending radially from the first central part; and erecting the first tabs up from the first central part.

Other objects, advantages and features of the present invention will become more apparent upon reading of the following non-restrictive description of specific embodiments thereof, given by way of example only with reference to the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

In the appended drawings:

FIG. 1 is a top perspective view of a heat dissipating device according to an embodiment of an aspect of the present invention;

FIG. 2 shows schematical views of 2 a) a metal sheet; 2 b) a heat dissipating device and 2 c) detail of FIG. 2 a), according to an embodiment of an aspect of the present invention;

FIG. 3 shows schematical views of: a heat dissipating device according to an embodiment of an aspect of the present invention: a) top view; b) side view; and c) perspective view;

FIG. 4 is a cross section showing a heat dissipating device in a fixed trim according to an embodiment of an aspect of the present invention;

FIGS. 6 are: a) and c) perspective views of a heat dissipating device according to an embodiment of an aspect of the present invention; b) and d) perspective views of a prior art heat dissipating device; and

FIGS. 7 are: a) and c) perspective views of a heat dissipating device according to an embodiment of an aspect of the present invention; b) and d) perspective views of a prior art heat dissipating device.

DESCRIPTION OF EMBODIMENTS OF THE INVENTION

There is generally provided a heat dissipating device, based on natural convection cooling or forced convection cooling. In the following, it will be described as a heat sink for use in light housings, such as in recessed LED light housings for example, but could be used in other applications.

As illustrated for example in FIG. 1, a heat sink 10 according to an embodiment of an aspect of the present invention generally comprises a base 12 supporting a plurality of heat-dissipating fins 14.

The base 12 is intended to be placed in contact with a heat emitter (not shown in FIG. 1).

The fins 14 extend from the base 12 at an angle α (see FIG. 3 c), on at least part of a periphery of the base 12, leaving the main surface of the base 12 free of fins 14. The angle α may be selected in the range between 0 ° and 90°, depending on the application. Such orientation of the fins 14 in relation to the base 12 is found to force air to flow towards the center of the base 12, thereby improving heat dissipation, so that heat is more effectively dissipated.

The fins 14 have a length generally determined by the geometry of the light housing, and are shown herein having a trapezoidal shape. Other shapes and different lengths are possible, depending on the requirements of specific installation, such as mobile trims for example (see FIG. 5).

The heat sink 10 may be made in a single metal sheet as now described.

As shown in FIG. 2 a, a metal sheet 10′ is cut out into a disk with a central part 12′ and tabs 14′ extending radially from the central part 12′, by die stamping or progressive die stamping for example. Holes 13 may be provided in the central part to allow air circulation. Then the tabs 14′ are erected up from the central part 12′, by folding along folding lines (F) (see FIG. 2 c), so as to form fins 14 standing up away from a base 12 at an angle α (see FIG. 2 b). There may be an overlap between consecutive fins 14 (see FIGS. 3 a and 3 b, and FIGS. 2 b and 3 c).

The material of the metal sheet is selected to have a good heat transfer capacity as well as a mechanical resistance. Aluminum may be used for example.

As best seen in FIGS. 4 to 6, a heat sink 10 according to an embodiment of an aspect of the present invention is positioned in a recessed light housing (H) with the base 12 thereof in contact with the heat emitter 16, the fins 14 extending up from the perimeter of the base 12 towards a part of the light housing (H) typically exposed to cooler air compared to the region of the heat emitter 16.

The angled orientation of the fins 14 relative to the base 12 (angle α) allows accommodating air passages for the air to flow away from the base 12 between the fins 14, thereby increasing the cooling surface provided by the fins 14, compared to fins extending perpendicularly to the base 12 for example.

Moreover, as shown in FIG. 4, the angled orientation of the fins 14 relative to the base 12 (angle α) allows nesting a first heat sink 10 a, comprising a base 12 a and fins 14 a, into a second heat sink 10 b, comprising a base 12 b and fins 14 b for example, the base 12 a of the first heat sink 10 a resting on the base 12 b of the second heat sink 10 b in contact with the heat emitter 16, thereby further increasing the flow of heated air away from the heat emitter 16 through the bases 12 a and 12 b along fins 14 a and 14 b.

In an embodiment illustrated in FIG. 5, the heat sink 10 is affixed to a mobile light trim 19.

Comparative tests were performed to assess the performances of heat sinks according to embodiments of the present invention, as will now be described in relations to FIGS. 6 to 8.

In FIG. 6 a, a heat sink 60 is compared with a heat sink 100 according to an embodiment of the present invention. The heat sink 60 is an extruded aluminum module machined to match the shape and geometry of recessed light housings, and black anodized for increased heat dissipation as well known in the art. The heat sink 60 comprises a base 62 supporting a plurality of plates 64 arranged across the surface of the base 62 and extending perpendicular from the base 62. The heat sink 100 comprises a first heat sink 10 a, comprising a base 12 a and fins 14 a, nested into a second heat sink 10 b, comprising a base 12 b and fins 14 b for example, the base 12 a of the first heat sink 10 a resting on the base 12 b of the second heat sink 10 b in contact with the heat emitter 16, as described hereinbefore.

As shown in FIGS. 6 b and 6 c, with a volume greatly reduced compared to that of the heat sink 60, the heat sink 100 provides a similar, even slightly increased, dissipation surface.

In FIG. 7 a, a heat sink 200 is compared with a heat sink 110 according to an embodiment of an aspect of the present invention. The heat sink 200 is a cast module, also black anodized for increasing the surface emissivity. The heat sink 200 comprises a base supporting a plurality of pin fins 210 arranged across the surface of the base and extending perpendicular from the base. The heat sink 110 comprises a base supporting a plurality of fins 14 extending at an angle therefrom about the perimeter of the base, as described hereinbefore.

As shown in FIGS. 7 b and 7 c, with a volume reduced compared to that of the heat sink 200, the heat sink 110 according to an embodiment of the present invention provides an increased dissipation surface.

Three temperature probes were attached to each heat sink, at equivalent positions relative to the heat sinks (see FIGS. 6 a and 7 a), so as to monitor the temperature at the heat source and at a maximum distance from the heat source, as well as at the center of the heat sinks. The heat sinks were placed in a temperature and humidity controlled test chamber, which temperature was monitored (see column 3 in Tables I and II).

For the heat sinks 60 and 200, the temperature of the heat source (i.e. immediately under the base of the heat sinks), of the heat sinks in their center, and of the heat sinks on a most exterior point thereof (column 4-6 in Tables I and II respectively) were monitored.

For the heat sinks 100 and 110 according to embodiments of the present invention, the temperature of the heat source, of the heat sinks in their center, and of the heat sinks on their exterior (column 7-9 in Tables I and II) were monitored.

As can be seen from Tables I and II, the heat sinks according to embodiments of the present invention provide an optimized ratio between working (i.e. heat dissipating) surface and volume of material needed for their manufacture, for application in light housings, such as led light housings for example.

As people in the art will appreciate, the present system and method may be used to dissipate heat in computer devices, electric motors, heating radiators, conditioning devices etc.

Although the present invention has been described hereinabove by way of embodiments thereof, it may be modified, without departing from the nature and teachings of the subject invention as claimed herein 

1. A heat dissipating device, comprising a first base adapted to be placed in contact with a heat emitter and first heat-dissipating fins extending from said first base on at least part of a periphery of said first base.
 2. The heat dissipating device of claim 1, wherein said first heat-dissipating fins extend from said first base at a first angle.
 3. The heat dissipating device of claim 1, wherein said first heat-dissipating fins extend from said first base on at least part of a periphery of said first base, a main surface of said first base remaining free of said first fins.
 4. The heat dissipating device of claim 1, wherein said first base and said first fins are made from a metal sheet.
 5. The heat dissipating device of claim 1, comprising a second base adapted to be placed in contact with said first base and second heat-dissipating fins extending from at least part of a periphery of said second base at a second angle.
 6. The heat dissipating device of claim 1, wherein said first base comprises holes therein.
 7. The heat dissipating device of claim 5, wherein said second base comprises holes therein.
 8. The heat dissipating device of claim 5, wherein at least one of said first and said second bases comprises holes therein.
 9. A method of fabricating a heat dissipating device, comprising: providing a first sheet of heat conductive and mechanically resistant material; cutting, out of the first sheet of material, a first piece comprising a first central part and first tabs extending radially from the first central part; and erecting the first tabs up from the first central part.
 10. The method of claim 9, wherein said erecting the first tabs up from the first central part comprises folding the first tabs up away from the first central part at a first angle.
 11. The method of claim 9, wherein said providing a first sheet comprises providing a sheet comprising aluminum.
 12. The method of claim 9, further comprising positioning the heat dissipating device with the first central part in contact with a heat emitter, the first tabs extending up from the perimeter of the first central part away from the heat emitter.
 13. The method of claim 9, further comprising: providing a second sheet of heat conductive and mechanically resistant material; cutting, out of the second sheet of material, a second piece comprising a second central part and second tabs extending radially from the second central part; erecting the second tabs up from the second central part; placing said first central part in contact with a heat emitter, said first tabs extending from said first central part on at least part of a periphery of said first central part; and placing said second central part in contact with said first central part, said second tabs extending from said second central part on at least part of a periphery of said second central part.
 14. The method of claim 9, further comprising providing holes in the first central part.
 15. The method of claim 9, further comprising: providing a second sheet of heat conductive and mechanically resistant material; cutting, out of the second sheet of material, a second piece comprising a second central part and second tabs extending radially from the second central part; providing holes in at least one of the first central part and the second central part; erecting the second tabs up from the second central part; placing said first central part in contact with a heat emitter, said first tabs extending from said first central part on at least part of a periphery of said first central part; and placing said second central part in contact with said first central part, said second tabs extending from said second central part on at least part of a periphery of said second central part. 